Complex spine surgery (CSS) addresses many conditions as deformity, degenerative, tumoral and traumatic pathology. Surgery is aimed at restauring function and balance of the spine, reducing pain, decompressing the neural elements, and stabilizing the spine.
CSS needs special instuments like screws, rods, and intervertebral implants.

Degenerative pathology includes mainly complex spine deformities.
The most challenging id adult degenerative lumbar scoliosis and deformity. Surgery is proposed when conservative treatment fails.
Correction and fixation of the scoliotic spine is undertaken after thorough study of the hole spinal equilibrium with the EOS stereoradiography system, which permits simultaneous orthogonal full spine X-rays with minimal irradiation.
Below left: pre-op.
Below right: post-op.

Other spine deformities include spondylolisthesis (antelisthesis or retrolisthesis), or slipping of a vertebra over another. (see image below).

Below is pre- and post-operative all posterior reduction of High Grade Spondylolisthesis in a teenage child

Tumoral complex spine surgery
aims total or near-total resection of the tumor, would it be a primitive tumor or a metastasis, and stabilization of the spine to prevent instability, which causes pain and neurologic symptoms.
Below is a C5C6 chordoma invading the prevertbral soft tissue, the vertebral bodies, the spinal canal. Total resection was done, aided by the mobilization of the right vertebral artery.Resection was followed by osteosynthesis using an artificial expandable vertebral body, a plate a plate and 4 screws.